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You searched for: subject:"robustness"
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[texts]A New Echo Hiding Algorithm with High Robustness
Echo hiding method boasts high watermark capacity but nothigh robustness. We propose a new echo hiding methodtaking advantage of both channels to replace the originalsingle echo hiding algorithm. Then, we propose a new echohiding algorithm combined with spread spectrum algorithmin Modulated Complex Lapped Transform domain. Theexperimental results show higher robustness compared withoriginal echo hiding method.
Keywords: Echo Hidin; Robustness; Channel; Capacity
Downloads: 15
[texts]Data Fusion in Wind Tunnel Testing; Combined Pressure Paint and Model Deformation Measurements (Invited) - Bell, James H.
As the benefit-to-cost ratio of advanced optical techniques for wind tunnel measurements such as Video Model Deformation (VMD), Pressure-Sensitive Paint (PSP), and others increases, these techniques are being used more and more often in large-scale production type facilities. Further benefits might be achieved if multiple optical techniques could be deployed in a wind tunnel test simultaneously. The present study discusses the problems and benefits of combining VMD and PSP systems...
Keywords: SUBSTRUCTURES; COMPUTATION; ROBUSTNESS (MATHEMATICS); COORDINATES; COMPENSATORS; ANALOGIES
Downloads: 75
[texts]Treatment of outliers in samples of size three (Volume 70B) - Anscombe, F. J.
Journal of Research of the National Bureau of Standards
Keywords: Statistics; outliers; residuals; estimation; robustness; least squares
Downloads: 41
[texts]Pseudo-likelihood Inference for Gaussian Markov Random Fields
Gaussian Markov random fields (GMRFs) are an important example of MRFs with many applications, particularly because GMRFs are known to provide effective approximations to any MRF. Despite their relative computational simplicity, inference in GMRFs using maximum likelihood (ML) is not always feasible. Therefore, this paper compares the inference quality using the pseudolikelihood, a well-known computational shortcut to full ML, and in addition the generalized lambda distribution is simulated to i...
Keywords: Gaussian Markov Random Fields; Pseudolikelihood; Robustness
Downloads: 11
[texts]Analysis of Robustness Sliding Mode Control Method for Active Suspension System
Taking vehicle transport into consideration, there are major systems that play important roles from the road to the body of the car to ensure the comfortability of the passengers. For that matter, the goal of car manufacturers is to develop the best suspension systems to guarantee this. In this article, active suspension system using a model of slide controller has been introduces with the purpose of advancing the comfort zone and accelerating vertically on passengers in the car...
Keywords: Robustness; Mode Control; Active Suspension System
Downloads: 9
[texts]JHU Participation in 'Mission Scientist on the European Space Agency's Infrared Space Observatory' - Neufeld, David A
The research funded work in support of the ISO GTO program ''Measurement of water vapor and oxygen abundances.'' Specific research included: (1) Theoretical modeling of the far-infrared water emission expected from shocked interstellar regions: (2) Theoretical modeling of the far-infrared water emission expected from circumstellar outflows from oxygen-rich evolved stars; (3) planning ISO observations, to test the predictions obtained through the modeling; and (4) Analyzing and interpreting far-i...
Keywords: ATTITUDE (INCLINATION); ROBUSTNESS (MATHEMATICS); STATISTICAL ANALYSIS; POLYNOMIALS; ALGORITHMS; EIGENVALUES; QUATERNIONS
Downloads: 17
[texts]Ho:Tm:Er:LuAG and Two Wavelength Oscillation - Barnes, Norman P.
Ho:Tm:Er:LuAG demonstrated simultaneous laser oscillation associated with two different transitions and different atoms. Two wavelength oscillation, or TWO, can be achieved in a single laser and single resonator. Moreover, the wavelength can be electronically controlled by varying the pump pulse length, Either the short wavelength, the Ho (5)1(sub 7) to (5)1(sub 8) transition at 2.1 microns, or the long wavelength, the Er (4)1(sub 11/2) to (4)1(sub 13/2) transition at 2.7 microns, or both wavele...
Keywords: EIGENVALUES; MATHEMATICAL MODELS; FORMULATIONS; DATA PROCESSING; ROBUSTNESS (MATHEMATICS); FREQUENCIES
Downloads: 74
[texts]Ground-Laboratory to In-Space Effective Atomic-Oxygen Fluence Determined for DC 93-500 Silicone - deGroh, Kim K.
Surfaces on the leading edge of spacecraft in low Earth orbit (e.g., surface facing the velocity direction), such as on the International Space Station, are subject to atomic oxygen attack, and certain materials are susceptible to erosion. Therefore, ground-based laboratory testing of the atomic oxygen durability of spacecraft materials is necessary for durability assessment when flight data are not available...
Keywords: ROBUSTNESS (MATHEMATICS); RUNWAYS; PRECISION; PROTOTYPES; SPACING; AIRPORTS; ROUTES
Downloads: 106
[texts]Formation of the stable auroral arc that intensifies at substorm onset - Lyons, L. R.
In a companion paper, we present observational evidence that the stable, growth-phase auroral arc that intensifies at substorm expansion phase onset often forms on magnetic field lines that map to within approximately 1 to 2 R(sub e) of synchronous. The equatorial plasma pressure is 1 to 10 nPa in this region, which can give a cross-tail current greater than 0.1 A/m. In this paper, we propose that the arc is formed by a perpendicular magnetospheric-current divergence that results from a strong d...
Keywords: POLYNOMIALS; ROBUSTNESS (MATHEMATICS); STABILITY; TRANSFER FUNCTIONS; COEFFICIENTS; LINEAR SYSTEMS
Downloads: 52
[texts]Optimization of Supersonic Transport Trajectories - Ardema, Mark D.
This paper develops a near-optimal guidance law for generating minimum fuel, time, or cost fixed-range trajectories for supersonic transport aircraft. The approach uses a choice of new state variables along with singular perturbation techniques to time-scale decouple the dynamic equations into multiple equations of single order (second order for the fast dynamics). Application of the maximum principle to each of the decoupled equations, as opposed to application to the original coupled equations...
Keywords: DESIGN ANALYSIS; ROBUSTNESS (MATHEMATICS); STATISTICAL ANALYSIS; OPTIMIZATION; SAMPLING; SHEAR STRESS
Downloads: 108
[texts]An MDOE Assessment of Nozzle Vanes for High Bypass Ratio Jet Noise Reduction - Henderson, Brenda
The effect of airfoil-shaped vanes placed in the fan stream of a BPR 8 coannular nozzle model system on the resulting jet noise was investigated. The experiments used a Modern Design of Experiments approach to investigate the impact of a range of vane parameters on the noise reduction achieved at representative takeoff conditions. The experimental results showed that the installation of the vanes decreased low frequency noise radiation in the downstream peak-noise direction and increased high fr...
Keywords: MACHINE LEARNING; ROBUSTNESS (MATHEMATICS); GRADIENTS; TEMPORAL RESOLUTION; CONSTRAINTS; TRADEOFFS; DISTANCE
Downloads: 58
[texts]Dual-layer Digital Image Watermarking for Intellectual Property Right Protection
Digital watermarking is a technique which is widelyused in various application areas such as copyright protection,copy control, broadcast monitoring etc. In this paper a noveldigital image watermarking technique is presented. To protectthe intellectual property rights, two different watermarks areinserted in host image. The first watermark is used to monitorthe any changes made in host image while second one is usedas proof of ownership...
Keywords: Digital Watermarking; Discrete Wavelet Transform; Fragile Watermark; LSB; Robustness
Downloads: 18
[texts]Numerical studies of the conventional impact damper with discrete frequency optimization and uncertainty considerations - Ehsan Dehghan-Niri; S.M. Zahrai; A.F. Rod
Abstract This paper presents the performance of a single horizontal conventional Impact Damper (ID) in both wide range frequency and resonance excitations. The effects of the coefficient of restitution, e, mass ratio, Î, and clearance, d, on the performance of ID are investigated. The optimal parameters are numerically found by discretely varying the clearance and excitation frequency. The performance of optimal ID is discussed, with respect to different parameters, in both resonance and off-re...
Keywords: Impact damper; Robustness; Resonance; Coefficient of restitution; Uncertainty
Downloads: 48
[texts]ACTIVE VIBRATION CONTROL OF SEISMICALLY EXCITED STRUCTURES BY ATMDS: STABILITY AND PERFORMANCE ROBUSTNESS PERSPECTIVE - ARASH MOHTAT; AGHIL YOUSEFI-KOMA; EHSAN DEHGHAN-NIRI
This paper demonstrates the trade-o® between nominal performance and robustness in intelligent and conventional structural vibration control schemes; and, proposes a systematic treatment of stability robustness and performance robustness against uncertainty due to structural damage. The adopted control strategies include an intelligent genetic fuzzy logic controller (GFLC) and reduced-order observer-based (ROOB) controllers based on pole-placement and linear quadratic regulator (LQR) conventi...
Keywords: Stability robustness; performance robustness; uncertainty due to damage; genetic fuzzy logic controller (GFLC); pole-placement; LQR; bridge; ATMD system
Downloads: 268
[movies]Digital Tipping Point: computer science student Josh Abraham 02 - Christian Einfeldt
This is one of many short video segments which will be added to the Digital Tipping Point (DTP) archive. In this segment, Josh Abraham recounts his memories of preparing web pages using Linux (GNU/Linux) on a 486 as opposed to using Notepad under Microsoft Windows. He says that he was able to keep 12 console terminal windows open under Linux, which made his work much faster than under Microsoft Windows...
Keywords: Josh Abraham; Abraham, Josh; Coolness Of Open Source Software; Linux, Robustness Of
Downloads: 729
[texts]EFFECTIVENESS ROBUSTNESS COMPROMISE FOR OPTIMUM DESIGN OF MTMD SYSTEMS THROUGH MULTI OBJECTIVE GA OPTIMIZATION - Ehsan Dehghan-Niri; A. Mohtat; S. M. Zahrai
Multiple tuned mass dampers (MTMD) consisting of many TMDs with equally distributed natural frequencies are considered for attenuating effectively the response of uncertain structures to harmonic force excitation. Considering the uncertainty in the natural frequency of the structural mode being controlled, the concept of nominal effectiveness is not the only aspect that characterizes performance; the robust effectiveness must also be addressed...
Keywords: multiple tuned mass damper (MTMD); optimal design methodology; effectiveness; robustness; multi-objective GA; Pareto-optimal solutions
Downloads: 241
[texts]NASA/DoD Aerospace Knowledge Diffusion Research Project. Paper 29: The US government technical report and the transfer of federally funded aerospace R and D - Pinelli, Thomas E.
This article discusses the U.S. government technical report and the transfer of federally funded aerospace research and development in a conceptual framework of the federal government as a producer of scientific and technical information. The article summarizes current literature and research and discusses U.S. government technical report use and the importance of using data obtained from the NASA/DoD Aerospace Knowledge Diffusion Research Project...
Keywords: CONTROL STABILITY; CONTROLLERS; COST ANALYSIS; MATHEMATICAL MODELS; ROBUSTNESS (MATHEMATICS); APPROXIMATION; PERTURBATION THEORY
Downloads: 59
[texts]Predicted and measured strain responses of isotropic panels to base excitation - Lyle, Karen H.
The accuracy of classical linear theory for predicting acceleration and strain for cantilevered and Clamped-Free-Clamped-Free (C-F-C-F) panels excited through the base is studied. Aluminum, steel and titanium plates of various dimensions and thicknessess were vibration tested, using a broadband random signal applied through a shaker mounting fixture. The strains were measured at 9 locations on the cantilevered panels and at 5 locations on the C-F-C-F panels...
Keywords: ADAPTIVE CONTROL; PHASES; EXCITATION; LINEAR SYSTEMS; ROBUSTNESS (MATHEMATICS); ALGORITHMS; CONVERGENCE; COVARIANCE; LEAST SQUARES METHOD; MATRICES (MATHEMATICS)
Downloads: 71
[texts]Keeping a Spacecraft on the Sun-Earth Line - Roithmayr, Carlos M.
Measurements of Earth's atmosphere as it occults sunlight can be obtained advantageously from a spacecraft placed in the proximity of the Sun-Earth Lagrange point L2. Maintaining the condition of continuous solar occultation by all parts of the atmospheric disk requires that the displacement of the spacecraft perpendicular to the Sun-Earth line remains less than 200 km. However, the gravitational force exerted by the Earth's moon must be negated by propulsion in order to meet this rather tight c...
Keywords: ALGORITHMS; MONKEYS; EVOKED RESPONSE (PSYCHOPHYSIOLOGY); BIOELECTRIC POTENTIAL; MAGNETIC FIELDS; ELECTRIC FIELDS; VARIABILITY; SIMULATION; ROBUSTNESS (MATHEMATICS); NEURONS
Downloads: 64
[movies]Dan Stowell research video, QMROD 2008: Robustness of vocal timbre features in live performance contexts - Dan Stowell
A short (3-minute) video lecture on my research into "Robustness of vocal timbre features in live performance contexts"
Keywords: research; audio; digital; music; voice; singing; speech; beatboxing; robustness; timbre; features; signal processing
Downloads: 506
[texts]Software Engineering Laboratory Series: Proceedings of the Twenty-Second Annual Software Engineering Workshop - NON
The Software Engineering Laboratory (SEL) is an organization sponsored by NASA/GSFC and created to investigate the effectiveness of software engineering technologies when applied to the development of application software. The activities, findings, and recommendations of the SEL are recorded in the Software Engineering Laboratory Series, a continuing series of reports that includes this document.
Keywords: COMPUTER PROGRAMS; ICE FORMATION; VARIABILITY; DATA BASES; ROBUSTNESS (MATHEMATICS); WEATHER; SPACING; SHAPES
Downloads: 329
[texts]Funtools: Fits Users Need Tools for Quick, Quantitative Analysis - Mandel, Eri
The Funtools project arose out of conversations with astronomers about the decline in their software development efforts over the past decade. A stated reason for this decline is that it takes too much effort to master one of the existing FITS libraries simply in order to write a few analysis programs. This problem is exacerbated by the fact that astronomers typically develop new programs only occasionally, and the long interval between coding efforts often necessitates re-learning the FITS inte...
Keywords: UPWIND SCHEMES (MATHEMATICS); UNSTRUCTURED GRIDS (MATHEMATICS); FACTORIZATION; ROBUSTNESS (MATHEMATICS); COMPUTATIONAL FLUID DYNAMICS; TRIANGLES
Downloads: 55
[texts]Thermal Insulation Performance of Flexible Piping for Use in HTS Power Cables - Fesmire, James E.
High-temperature superconducting (HTS) cables that typically operate at temperatures below 80 K are being developed for power transmission. The practical application of HTS power cables will require the use of flexible piping to contain the cable and the liquid nitrogen coolant. A study of thermal performance of multilayer insulation (MLI) was conducted in geometries representing both rigid and flexible piping...
Keywords: ACTUATORS; CONTROLLERS; DEGRADATION; FAILURE ANALYSIS; FLEXIBLE BODIES; CONTROL SYSTEMS DESIGN; ROBUSTNESS (MATHEMATICS)
Downloads: 175
[texts]A method for tailoring the information content of a software process model - Perkins, Sharon
The framework is defined for a general method for selecting a necessary and sufficient subset of a general software life cycle's information products, to support new software development process. Procedures for characterizing problem domains in general and mapping to a tailored set of life cycle processes and products is presented. An overview of the method is shown using the following steps: (1) During the problem concept definition phase, perform standardized interviews and dialogs between dev...
Keywords: ARTIFICIAL INTELLIGENCE; CONTROL SYSTEMS DESIGN; FAULT TOLERANCE; NEURAL NETS; RELIABILITY ENGINEERING; ROBUSTNESS (MATHEMATICS); MAINTAINABILITY; REDUNDANCY
Downloads: 186
[texts]Hypersonic Boundary Layer Stability over a Flared Cone in a Quiet Tunnel - Lachowicz, Jason T.
Hypersonic boundary layer measurements were conducted over a flared cone in a quiet wind tunnel. The flared cone was tested at a freestream unit Reynolds number of 2.82x106/ft in a Mach 6 flow. This Reynolds number provided laminar-to-transitional flow over the model in a low-disturbance environment. Point measurements with a single hot wire using a novel constant voltage anemometry system were used to measure the boundary layer disturbances...
Keywords: SYSTEMS ENGINEERING; ACTUATORS; CONTROL SYSTEMS DESIGN; FLEXIBLE BODIES; DISSIPATION; FEEDBACK CONTROL; NONLINEAR PROGRAMMING; ROBUSTNESS (MATHEMATICS)
Downloads: 119
[texts]On The Computational Capabilities of Physical Systems - Wolpert, David H
In the first of this pair of papers, it was proven that there cannot be a physical computer to which one can properly pose any and all computational tasks concerning the physical universe. It was then further proven that no physical computer C can correctly carry out all computational tasks that can be posed to C. As a particular example, this result means that no physical computer that can, for any physical system external to that computer, take the specification of that external system's state...
Keywords: AIRFOILS; SHAPE OPTIMIZATION; STATISTICAL ANALYSIS; COMPUTATIONAL FLUID DYNAMICS; MACH NUMBER; COMPUTATIONAL GRIDS; ROBUSTNESS (MATHEMATICS); AERODYNAMIC DRAG
Downloads: 113
[texts]Calibration of the Langley 8-Foot High Temperature Tunnel for Hypersonic Airbreathing Propulsion Testing - Huebner, Lawrence D.
The NASA Langley 8-Foot High Temperature Tunnel has recently been modified to produce a unique testing capability for hypersonic airbreathing propulsion systems. Prior to these modifications, the facility was used primarily for aerothermal loads and structural verification testing at true flight total enthalpy conditions for Mach numbers between 6 and 7. One of the recent modifications was an oxygen replenishment system which allows operating airbreathing propulsion systems to be tested at true ...
Keywords: MULTIVARIABLE CONTROL; DESIGN ANALYSIS; FEEDBACK; SUBSTRUCTURES; STIFFNESS MATRIX; MODELS; ROBUSTNESS (MATHEMATICS)
Downloads: 58
[texts]Higher Harmonic Control for Tiltrotor Vibration Reduction - Nixon, Mark W.
The results of a joint NASA/Army/Bell Helicopter Textron wind-tunnel test to assess the potential of higher harmonic control (HHC) for reducing vibrations in tiltrotor aircraft operating in the airplane mode of flight, and to evaluate the effectiveness of a Bell-developed HHC algorithm called MAVSS (Multipoint Adaptive Vibration Suppression System) are presented. The test was conducted in the Langley Transonic Dynamics Tunnel using an unpowered 1/5- scale semispan aeroelastic model of the V-22 w...
Keywords: ATTITUDE CONTROL; CONTROL THEORY; SIMULATION; SMALL SATELLITE TECHNOLOGY; NONLINEAR PROGRAMMING; ROBUSTNESS (MATHEMATICS); SPACECRAFT CONTROL
Downloads: 105
[texts]Impact of a process improvement program in a production software environment: Are we any better - Heller, Gerard H.
For the past 15 years, Computer Sciences Corporation (CSC) has participated in a process improvement program as a member of the Software Engineering Laboratory (SEL), which is sponsored by GSFC. The benefits CSC has derived from involvement in this program are analyzed. In the environment studied, it shows that improvements were indeed achieved, as evidenced by a decrease in error rates and costs over a period in which both the size and the complexity of the developed systems increased substanti...
Keywords: MONTE CARLO METHOD; LOCI; PROBABILITY THEORY; ROBUSTNESS (MATHEMATICS); STABILITY; STOCHASTIC PROCESSES; ACTUATORS; BINARY DATA; ESTIMATES; HISTOGRAMS
Downloads: 62
[texts]High Capacity Robust Medical Image Data Hiding using CDCS with Integrity Checking
While transferring electronic patient report (EPR)data along with corresponding medical images over network,confidentiality must be assured. This can be achieved byembedding EPR data in corresponding medical image itself.However, as the size of EPR increases, security androbustness of the embedded information becomes major issueto monitor. Also checking the integrity of this embedded datamust be needed in order to assure that retrieved EPR data isoriginal and not manipulated by different types o...
Keywords: Medical image; EPR; Data hiding; Stego image; ROI; Robustness; Security; Integrity Check
Downloads: 10
[texts]A process for preparing an ultra-thin, adhesiveless, multi-layered, patterned polymer substrate - NON
A process for preparing an ultra-thin, adhesiveless, multi-layered, patterned polymer substrate is disclosed. The process may be used to prepare both rigid and flexible cables and circuit boards. A substrate is provided and a polymeric solution comprising a self-bonding, soluble polymer and a solvent is applied to the substrate. Next, the polymer solution is dried to form a polymer coated substrate...
Keywords: SYSTEMS STABILITY; RICCATI EQUATION; ENERGY DISSIPATION; LINEAR SYSTEMS; ROBUSTNESS (MATHEMATICS); STABILIZATION; CONTROLLERS; INEQUALITIES
Downloads: 72
[texts]Study of auroral dynamics with combined spacecraft and incoherent scatter radar data - Thayer, Jeffrey P.
The objectives of this project were to study the coupling between the ionosphere and the magnetosphere, and to understand how this coupling was affected by changes in the solar wind. The data used consisted of satellite measurements coordinated with Sondrestrom incoherent scatter radar observations. We focused our efforts on the study of temporal and spatial changes in the dayside auroral precipitation and electric field.
Keywords: INVERSE KINEMATICS; MANIPULATORS; ROBUSTNESS (MATHEMATICS); WEIGHTING FUNCTIONS; APPROXIMATION; MATRICES (MATHEMATICS); SINGULARITY (MATHEMATICS); TELEOPERATORS
Downloads: 61
[texts]18. A Novel Technique.full
Proposed paper present a new robust watermarking technique for copyright protection based on Discrete Wavelet Transform and Singular Value Decomposition. The Low frequency sub band of the wavelet decomposed cover image is modified by modifying its singular values. A secret key is generated from the original watermark with the help of visual cryptography to claim the ownership of the image. The ownership of the image can be claimed by superimposing this secret key on the extracted watermark from ...
Keywords: Image Watermarking; Visual Cryptography; Singular Value Decomposition; Discrete WaveletTransform; Robustness; Steganography
Downloads: 13
[texts]Analytical Prediction of Damage Growth in Notched Composite Panels Loaded in Axial Compression - Ambur, Damodar R.
A progressive failure analysis method based on shell elements is developed for the computation of damage initiation and growth in stiffened thick-skin stitched graphite-epoxy panels loaded in axial compression. The analysis method involves a step-by-step simulation of material degradation based on ply-level failure mechanisms. High computational efficiency is derived from the use of superposed layers of shell elements to model each ply orientation in the laminate...
Keywords: PARAMETERIZATION; MATHEMATICAL MODELS; SET THEORY; UNCERTAIN SYSTEMS; FEASIBILITY ANALYSIS; SIMULATION; EIGENVALUES; ROBUSTNESS (MATHEMATICS); LINEAR TRANSFORMATIONS
Downloads: 89
[texts]Effectiveness-robustness objectives in MTMD system design: An evolutionary optimal design methodology - Ehsan Dehghan-Niri; S. M. Zahrai;A. Mohtat
The main contribution pursued in this investigation is to propose a generic optimal methodology for designing multiple tuned mass damper (MTMD) systems to efficiently suppress the response of uncertain structures to harmonic excitations. This methodology comprises quantitative indexing of MTMD effectiveness and robustness as performance criteria, implementing a two objective optimization and presenting solutions as optimal set of non-dominated designs...
Keywords: multiple tuned mass damper (MTMD); optimal design methodology; effectiveness; robustness; multi-objective GA; Pareto-optimal solutions
Downloads: 271
[texts]Generalized frame work for robust design of tuned mass damper systems - A. Mohtat; Ehsan Dehghan-Niri
The primary purpose of this contribution is to develop a novel framework for generalized robust design of tuned mass damper(TMD)systems as passive vibration controllers for uncertain structures.This versatile strategy is intended to be free of any restriction on the structure TMD system configuration,the performance criterion,and the number of uncertain parameters.The main idea pursued is to adopt methods and concepts from the robust control literature,including:(1)the linear fractional transfor...
Keywords: multiple tuned mass damper (MTMD); Genetic Algorithm; effectiveness; robustness; multi-objective GA; Pareto-optimal solutions
Downloads: 312
[texts]Computation of Passive Robustness Bound for Assembly/Disassembly Processes
Works presented in this paper deal with the robustness ofmanufacturing job‐shops with time constraints. A computingalgorithm of a lower bound of the maximal time disturbancesallowed in a given point is provided. To demonstrate theeffectiveness and accuracy of this algorithm, two industrialexamples are depicted. The possession of this bound allowschecking the death of marks without the generation of toomany false alarms...
Keywords: P-time Petri Net; Manufacturing System; Passive Robustness; Sojourn Time Constraints; Time Disturbance
Downloads: 5
[texts]Progress of Multicolor Single Detector to Detector Array Development for Remote Sensing - Abedin, M. Nurul
Knowledge of the spatial and temporal distribution of atmospheric species such as CO2, O3, H2O, and CH4 is important for understanding the chemistry and physical cycles involving Earth s atmosphere. Although several remote sensing techniques are suitable for such measurements they are considered high cost techniques involving complicated instrumentation. Therefore, simultaneous measurement of atmospheric species using a single remote sensing instrument is significant for minimizing cost, size an...
Keywords: CERAMICS; THIN FILMS; THERMOCOUPLES; HIGH TEMPERATURE ENVIRONMENTS; ROBUSTNESS (MATHEMATICS); STABILITY; NOBLE METALS
Downloads: 85
[texts]Effects of Mean Flow Profiles on Instability of a Low-Density Gas Jet Injected into a High-Density Gas - Vedantam, Nanda Kishor
The objective of this study was to investigate the effects of the mean flow profiles on the instability characteristics in the near-injector region of low-density gas jets injected into high-density ambient gas mediums. To achieve this, a linear temporal stability analysis and a spatio-temporal stability analysis of a low-density round gas jet injected vertically upwards into a high-density ambient gas were performed by assuming three different sets of mean velocity and density profiles...
Keywords: ROBUSTNESS (MATHEMATICS); COMPUTATIONAL FLUID DYNAMICS; UNCERTAIN SYSTEMS; SENSITIVITY; DERIVATION; METHOD OF MOMENTS; RANDOM VARIABLES; APPROXIMATION; MONTE CARLO METHOD
Downloads: 52
[texts]Automated Inspection of the RSRM Case O-Ring Seal Surface - ODell, Keith P
An automated inspection system has been developed to inspect the o-ring sealing surfaces on the Space Shuttle reusable solid rocket motor (RSRM) case segment joints. A laser digitizing system is used to create a three dimensional map of the o-ring sealing surfaces. This data is analyzed for any irregularities, which are noted for further inspection and disposition. This paper describes both the hardware and the software used to gather data as well as the methods developed to analyze the data...
Keywords: COMPUTERIZED SIMULATION; PARACHUTES; TRAJECTORIES; MONTE CARLO METHOD; AEROMANEUVERING; MARS LANDING; DESIGN ANALYSIS; ROBUSTNESS (MATHEMATICS); RANDOM VARIABLES; SUPERSONICS; DEPLOYMENT
Downloads: 107
[texts]Technical evaluation report, AGARD Fluid Dynamics Panel Symposium on Effects of Adverse Weather on Aerodynamics - Reinmann, J. J
The purpose of the meeting on Effects of Adverse Weather on Aerodynamics was to provide an update of the stae-of-the-art with respect to the prediction, simulation, and measurement of the effects of icing, anti-icing fluids, and various precipitation on the aerodynamic characteristics of flight vehicles. Sessions were devoted to introductory and survey papers and icing certification issues, to analytical and experimental simulation of ice frost contamination and its effects of aerodynamics, and ...
Keywords: ARTIFICIAL INTELLIGENCE; ROBUSTNESS (MATHEMATICS); CONTROL THEORY; CONTROLLERS; FUZZY SETS; MICROPROCESSORS; CHIPS (ELECTRONICS); COMPUTER TECHNIQUES; EXPERT SYSTEMS; NONLINEAR SYSTEMS
Downloads: 212
[texts]A New Ultra Low-Power and Noise Tolerant Circuit Technique for CMOS Domino Logic
Dynamic logic style is used in high performance circuit design because of its fast speed and less transistors requirement as compared to CMOS logic style. But it is not widely accepted for all types of circuit implementations due to its less noise tolerance and charge sharing problems. A small noise at the input of the dynamic logic can change the desired output. Domino logic uses one static CMOS inverter at the output of dynamic node which is more noise immune and consuming very less power as c...
Keywords: Dynamic logic; domino logic; Delay; diode-footed domino; noise tolerance; power consumption; robustness; technology scaling; semi-dynamic logic
Downloads: 82
[texts]Fractal Characterization of Multitemporal Remote Sensing Data - Quattrochi, Dale A.
Scale is an ''innate'' concept in geographic information systems. It is recognized as something that is intrinsic to the capture, storage, manipulation, analysis, modeling, and output of space and time data within a GIS purview, yet the relative meaning and ramifications of scaling spatial and temporal data from this perspective remain enigmatic. As GISs become more sophisticated as a product of more robust software and more powerful computer systems, there is an urgent need to examine the issue...
Keywords: ROBUSTNESS (MATHEMATICS); COMPONENT RELIABILITY; STRUCTURAL ANALYSIS; ALGORITHMS; TWO DIMENSIONAL MODELS; COMPUTERIZED SIMULATION; FORMULATIONS; FREQUENCIES; DAMPING; DYNAMIC MODELS; DYNAMIC CONTROL
Downloads: 92
[texts]Copolyimides prepared from ODPA, BTDA and 3,4'-ODA - NON
A copolyimide was prepared by reacting 3,4'-oxydianiline (3,4'-ODA) with a dianhydride blend comprising, based on the total amount of the dianhydride blend, about 67 to 80 mole percent of 4,4'-oxydiphthalic anhydride (ODPA) and about 20 to 33 mole percent of 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA). The copolyimide may be endcapped with up to about 10 mole percent of a monofunctional aromatic anhydride and has unbalanced stoichiometry such that a molar deficit in the dianhydride ...
Keywords: HUMAN-COMPUTER INTERFACE; ROBUSTNESS (MATHEMATICS); MAN MACHINE SYSTEMS; NEURAL NETS; SPEECH; SPEECH RECOGNITION; VOICE CONTROL; ALGORITHMS; ROBOT CONTROL; ROBOTS
Downloads: 80
[texts]Aerothermal Heating Predictions for Mars Microprobe - Mitcheltree, R. A.
A combination of computational predictions and experimental measurements of the aerothermal heating expected on the two Mars Microprobes during their entry to Mars are presented. The maximum, non-ablating, heating rate at the vehicle's stagnation point (at alpha = 0 degrees) is predicted for an undershoot trajectory to be 194 Watts per square centimeters with associated stagnation point pressure of 0.064 atm...
Keywords: FLIGHT CONTROL; FLIGHT TESTS; RESEARCH VEHICLES; HYPERSONIC AIRCRAFT; PERFORMANCE PREDICTION; TRAJECTORY ANALYSIS; SUPERSONIC COMBUSTION RAMJET ENGINES; ROBUSTNESS (MATHEMATICS); STAGE SEPARATION
Downloads: 94
[texts]Space Vehicle Power System Comprised of Battery/Capacitor Combinations - Camarotte, C.
Recent improvements in energy densities of batteries open the possibility of using electric rather that hydraulic actuators in space vehicle systems. However, the systems usually require short-duration, high-power pulses. This power profile requires the battery system to be sized to meet the power requirements rather than stored energy requirements, often resulting in a large and inefficient energy storage system...
Keywords: CARTESIAN COORDINATES; GRID GENERATION (MATHEMATICS); THREE DIMENSIONAL FLOW; BOUNDARY CONDITIONS; UNSTEADY FLOW; ALGORITHMS; ROBUSTNESS (MATHEMATICS); SIMPLIFICATION; SIMULATION
Downloads: 84
[texts]Advanced power sources for space missions - Gavin, Joseph G., Jr.
Approaches to satisfying the power requirements of space-based Strategic Defense Initiative (SDI) missions are studied. The power requirements for non-SDI military space missions and for civil space missions of the National Aeronautics and Space Administration (NASA) are also considered. The more demanding SDI power requirements appear to encompass many, if not all, of the power requirements for those missions...
Keywords: ADAPTIVE CONTROL; LIAPUNOV FUNCTIONS; CONTROL SYSTEMS DESIGN; CONTROL THEORY; MANIPULATORS; ROBOT CONTROL; ROBOTICS; ROBOTS; ROBUSTNESS (MATHEMATICS); DYNAMIC CHARACTERISTICS
Downloads: 146
[texts]A Design Process for the Acoustical System of an Enclosed Space Colony - Hawke, Joann
Sounds of Silence. Using a general systems approach, factors and components of the acoustical design process for an isolated, confined space community in a torus space enclosure are considered. These components include the following: organizational structure and its effect on alternatives; problem definition and limits; criteria and priorities; methods of data gathering; modelling and measurement of the whole system and its components; decision methods; and design scenario of the acoustics of th...
Keywords: GALERKIN METHOD; SCATTERING; LINEARIZATION; UNSTRUCTURED GRIDS (MATHEMATICS); TIME DEPENDENCE; SIMULATION; EULER EQUATIONS OF MOTION; OBJECT-ORIENTED PROGRAMMING; ROBUSTNESS (MATHEMATICS); AEROACOUSTICS
Downloads: 135
[texts]Laboratory Measurements of Celestial Solids - Sievers, A. J.
Our experimental study has focused on laboratory measurements of the low temperature optical properties of a variety of astronomically significant materials in the infrared and mm-wave region of the spectrum. Our far infrared measurements of silicate grains with an open structure have produced a variety of unusual results: (1) the low temperature mass opacity coefficient of small amorphous 2MgO(central dot)SiO2 and MgO(central dot)2SiO2 grains are many times larger than the values previously use...
Keywords: DIRECTIONAL CONTROL; FIGHTER AIRCRAFT; LATERAL CONTROL; ROBUSTNESS (MATHEMATICS); FEEDBACK; AIRCRAFT PERFORMANCE; MATRICES (MATHEMATICS); STABILITY; FLIGHT CONTROL; COMPENSATORS; CONTROL EQUIPMENT
Downloads: 68
[texts]Temporal model of an optically pumped co-doped solid state laser - Wangler, T. G.
Currently, research is being conducted on the optical properties of materials associated with the development of solid state lasers in the two micron region. In support of this effort, a mathematical model describing the energy transfer in a holmium laser sensitized with thulium is developed. In this paper, we establish some qualitative properties of the solution of the model, such as non-negativity, boundedness, and integrability...
Keywords: CONFIGURATION MANAGEMENT; FLIGHT PLANS; PREDICTIONS; ROBUSTNESS (MATHEMATICS); SAFETY MANAGEMENT; CONSTRAINTS; MISSION PLANNING; RESOURCES MANAGEMENT; SCHEDULING; SPACE MISSIONS; AEROSPACE PLANES; FLEXIBILITY; FLIGHT OPERATIONS
Downloads: 44
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